Two-arm rotary drill bit



April 3, 1956 o. PHIPPS 2,740,612

' TWO-ARM ROTARY DRILL BIT Filed Feb. 25, 1954 2 Sheets-Sheet l INVENTOR. Orville Phipps April 3, 1956 o. PHIPPS 2,740,612

TWO-ARM ROTARY DRILL BIT Filed Feb. 23, 1954 2 Sheets-Sheet 2 IN V EN TOR.

Orville Phipps Attorney.

United States Patent 3 6 TWO-ARM ROTARY DRILL BIT Orville Phipps, near Denver, Colo.

Application February 23, 1954, Serial No. 412,024

8 Claims. (Cl. 255-61) I This invention relates to drill bits of rotary type applicable to the development of deep earth bores, such as gas and oil wells, and has as an object to provide a novel and improved such bit operable as the cutting element of conventional drilling equipment with high efliciency and enhanced penetrative effect.

A further object of the invention is to provide a novel and improved rotary-type drill bit characterized by long life in continuous working engagement with the foot of a bore under development thereby.

A further object of the invention is to provide a novel and improved rotary-type drill bit that is elfectively selfsharpening in use.

A further object of the invention is to provide a novel and improved rotary-type drill bit that is operatively selfcentered to minimize wandering and deviation from a straight-line bore axis.

A further object of the invention is to provide a novel and improved rotary-type drill bit substantially invariable as to effective diameter and consequent bore gauge during extended periods of use.

A further object of the invention is to provide a novel and improved rotary-type drill bit arranged for the circulation of coolant therethrough with excavation-assisting and enhanced scavenging effect.

A further object of the invention is to provide a novel and improved rotary-type drill bit of low operative cost, facile construction in a range of desired sizes, high operative durability, and advantageous performance.

With the foregoing and other objects in view, my invention consists in the construction, arrangement, and combination of elements as hereinafter set forth, pointed out in my claims, and illustrated by the accompanying drawings, in which- Figure 1 is an end elevation showing the working face of a typical drill bit exemplifying the principles and improvements of the invention. A

Figure 2 is a side elevation of the organization according to Figure 1.

Figure 3 is an edge elevation of the bit shown in the preceding views, a portion of the bit stem being broken away to conserve space.

Figure 4 is a cross section taken substantially on the indicated line 44 of Figure 1.

Figure 5 is a fragmentary, detail section, on a relatively enlarged scale, axially through a nozzle element utilized in the organization of the bit as shown.

Figure 6 is a view similar to Figure 1 showing a modified bit construction within the contemplation of the invention.

Figure 7 is a side elevation of the bit organization according to Figure 6.

Figure 8 is an edge elevation of the bit shown in the preceding views with a portion of the bit stem broken away to conserve space.

Figure 9 is a cross section taken substantially on the indicated line 9-9 of Figure 6.

The development of deep earth bores for the location 2,740,6l2 Patented Apr. 3, 1956 and production of oils and natural gases is extensively accomplished through the agency of a power-rotated line or string constituted from separable elements and furnished at its lower end with a removable and replaceable drill bit reactive to its rotation with the line or string to form and deepen a cylindrical excavation in a diameter somewhat greater than that of the line or string. To cool the working elements of the bit and to scavenge cuttings and loosened material from the bore, a flow of coolant, usually a thin water pulp or mud, is delivered under pressure through the hollow line or string and outwardly from the bit at the foot of the bore for uprise exteriorly about the bit and line or string and outwardly from the upper end of the bore. Manifestly, efiiciency in such operations is a function of the bit penetration in relation to the power applied to rotation thereof, long operative life of the bit in effective cutting relation with the foot of bore, maintenance of elfective bit diameter and consequent bore size through the working life of the bit, and maintained regulation of coolant discharge from the bit for maximum benefit in the excavating and scavenging operations, hence the instant invention is directed to the provision of a novel and improved drill bit of rotary type characterized by constructions and relationships promotive of drilling efficiency in the respects noted.

As shown in Figures 1-5, inclusive, a typical simple embodiment of the invention is represented as a unitary assembly of elements formed on or fixedly associated with a body 10 of suitable workable metal, such as alloy steel. The body 10 is cast, forged, or worked in any expedient manner to substantially the illustrated form and to provide a tapered, externally-threaded stem 11 coactible in any usual manner with the free end of the drill line or string to detachably mount the bit as a terminal extension thereon, to provide a block 12 extending laterally beyond and in shouldered relation with the stem 11 to a maximum at one diameter determinative of the bit size, and a pair of separate arms 13 outstanding from the side of the block 12 remote from the stem 11 in generally parallel relation with the axis of said stem about which the unit is designed to rotate. An arm 13 is pro vided on each maximum radial extension of the block 12, the outer side margins of said arms conforming to the circular arc contour limiting and determining the maximum diameter of the block, and inner margins of the arms 13 are separated in a like spacing away from the axis of bit rotation to provide a central trough or channel therebetween in a direction perpendicular to the maximum diameter of the block. Faces of the arms 13 trailing in the direction of bit rotation merge into the adjacent block surface, whereby to buttress said arms on the block, and the faces of said arms leading in the direction of rotation are staggered diametrically of the block as fiat planes 14 parallel to the axial plane through the block maximum diameter and each offset from said latter plane a like distance in the direction of bit rotation. The lead ing face planes 14 of the arms 13 are alike, face in opposite directions, have each a depth axially of the unit from the associated arm free end on the order of their width, and close to and in angular relation with a block surface 15 which inclines moderately outwardly of the block from a maximum elevation in the central trough or channel separating the arms at their inner margins.

The free ends of the arms 13 are the principal cutting elements of the tool and are formed to lie in a common plane perpendicular to the axis of bit rotation, a feature of the invention being the arming of said arm free ends with hard, abrasion-resistant inserts disposed to establish the actual cutting operations. To accommodate and securely seat the cutting inserts characterizing the improvement, the free end of each arm 13 is formed or provided 3 V with a relatively-deep, rectangular slot which extends from and opens through the inner and outer sides of the arm with the slot margin most nearly adjacent the associatedleading face plane 14 coincident with the maximum diameter of the block, and which intersects the tip of the arm entirely across the arm width; the depth of said slots paralleling the axis of bit rotation. Thus, the margins of the slots in the two arms most nearly adjacent the lead: ing face plane 14 of the associated arm align diametrically of the block 12 in registration with the maximum diameter thereof to which the leading face planes 14 are parallel, and the margins of the slots trailing in the direction of bit rotation are consequently parallel but offset one from the other a distance equal to twice the slotopen width. Formed to seat within and 'to .fill the slots interrupting the ends of the arms 13, rectangular wafers 16 of tungsten-carbide alloy material are provided in a width, or transverse dimension disposable axially of the bit, somewhat exceeding the depth of the slots wherein they are to be mounted, thus to provide a projection of such wafer along and outwardly beyond the free end of the arm 13 to which the wafer is applied. The wafers 16 are entered within and to fill the full depth of the slots pro vided for their reception and are permanently secured by welding or brazing, preferably with a silver bond, at and throughout the wafer and slot surfaces in contact, ends of the so-mounted wafers are ground into conformity with the inner and outer side margins of the associated arm, the exposed edge of the wafer substantially radial of the bit is ground into smooth conformity with the arm tip portion trailing in the direction of bit rotation and to a moderate pitch or rake appropriate to present a chisel edge in the direction of bit rotation, and the arm tip portion leading in the direction of bit rotation is beveled and inclined along the free margin of the associated face plane 14, and toward the latter, to expose a narrow fillet of the wafer chisel edge in position for effective cutting operations. Thus, the chisel edges of the two wafers 16 define a common line diametrically of the bit except where interrupted by the spacing between inner margins of the arms 13,, and the chisel edges of the separate wafers 16 pitch or rake in opposite directions but in identical relation to the direction of bit rotation. At the side of each wafer 16 trailing in the direction of bitrotat-ion the material backing the wafer at the tip of the associated arm .13 is dubbed away through a smooth curve from coplanar relation with the pitched chisel edge of the wafer and to smooth mergence with the trailing surface of the aim.

Integral with, or removably and replaceably aliixed to, the block '12 in and to substantially till the space between the separated inner margins of the arms 13, a cuneal boss 17 is disposed with its apex symmetrically and perpendicularly intersecting the .axis of 'bit rotation at right angles to the line common to the chisel edges of the wafers 16 and inwardly of the bit in .a substantial spacing from the said chisel edge line, the length of said boss along its apex being expediently such as to project the boss ends radially of the bit slightly beyond the planes of the adjacent arm faces 14. The normal apex of the boss 17 is cut away to provide a rectangular slot opening away from the block 12 and through both ends of the boss wherein is seated and permanently secured, as by welding or brazing, a rectangular wafer 18 of tungsten-carbide alloy arranged for projection of its :free edge slightly beyond the adjacent boss walls. Since the wafer 13 perpendicularly crosses the axis of bit rotation with uniform projection at each side thereof, it is expedient to oppositely pitch or incline the halves of the wafer free edge extending beyond the boss in such manner as to provide a chisel edge along each of the projected corners of the wafer leading in the direction of bit rotation.

In spaced relation with the outer end of each wafer '16, and preferably extending across the zone of function be tween each arm 13, leading face 14 and the adjacent block surface 15, a recess elongated in parallel with the bit axis of rotation intersects the arcuate outer edge of each arm 13 for the accommodation of a tungsten-carbide wafer 19 therein seated and permanently secured, as by welding or brazing, in conformity of its exposed surface with that of the arm wherein it is embedded.

Axially of the stem 11 and opening through the stem free end a relatively-large bore 20 is formed to determinate in a preferably domed or rounded inner end within the body 12, and a passage 21 leads at a moderate di vergence from the axis of bit rotation from the inner end of said bore to open through each block surface 15 adjacent and forwardly in the direction of bit rotation from the leading face plane 14 of each arm 13. When the bit is engaged by means of its stem 11 with an actuating drill string or line having a channel for the fiow of coolant therethrough, the bore 20 is adapted to register with and continue such channel and to direct .the coolant flow to and for ejection through the passages 21 with enhanced velocity due to the size proportions of the bore and passages. The location and inclination of the passages relative to other elements of the bit is such as to deliver a jet stream of coolant with washing effect across the leading .face planes 14 of the cutting arms 13 to fully clear, soften, and to some extent excavate the bore foot area immediately in advance of each wafer 16 chisel edge, and a further feature of the invention is the provision of means for maintaining the direction and for enhancing the velocity of the output from the passages 21 throughout the useful life of the tool. The cooling and scavenging agents commonly employed in deep drilling operations usually entrain a high percentage of solids which have notable abrasive properties under the pressures necessary to maintain circulation, hence the passages 21, and particularly the discharge mouths of said passages, would rapidly wear and deform unless protected, to which end the invention provides a nozzle .22 of tungsten-carbide alloy material seated and permanently secured in and .to constitute the delivery end of each passage 21. Each nozzle 22 is a generally tubular sleeve of appropriate length having a uniform exterior diameter slightly greater than the open diameter of the passage 21 wherewi'th it is to be associated and a bore or throat converging on -a preferably elliptical .curve from a diameter at .its inner end equal to that of the passage 21 and .a smaller diameter of opening at its outer end. The outer end of the passage 21 is counter-bored to receive the nozzle 22 and to seat the latter with its end of least opening flush with the block surface 15, in which position the said nozzle is welded or brazed to the block surfaces thereby engaged and the nozzle throat smoothly merges at its inner end with the bore of the passage 21 for smooth, eddy-free flow from the bore 20 and outwardly through the nozzle, the convergent :form of the nozzle throat developing an enhanced, high-jet velocity in its discharge.

Between the outer edge surfaces of the arms 13 which determine the maximum diameter of the bit, the side walls of the block 12 are smoothly and symmetrically contoured to establish a block diameter perpendicular to the bit maximum diameter that is considerably less than the latter, whereby to provide clearance at each side of the bit between the block and the bore walls wherethrough coolant ejected through the nozzles 22 may uprise with bore-scavenging etfect, and exterior corners of the block 12 underlying the fingers 13v may be chamfered, as at 23, to minimize any tendency of the bit to stick or hang as it is retracted within the bore.

The modified construction represented by Figures 6-9, inclusive, distinguishes from that herein'abov'e described only in the provision of deep notches 24 intersecting the free end of each arm 13 chordally of the bit and interrupting the full depth of the 'diametric slot designed for the accommodation ofa wafer 16. Each notch '24 distem hollow terminates in a domed chamber within the body, and the means for circulating coolant through the body comprises a passage small in relation to the chamber leading from the latter and diverging from the bit axis to open through the end of the body remote from the stern adjacent and forwardly in the direction of bit rotation from each of said arms, and a tungstemcarbide nozzle permanently seated in the body in smooth flow registration with and to constitute the discharge end of each said passage.

8. The organization according to claim 1, wherein the stem hollow terminates in a domed chamber within the body, a passage small in relation to the chamber leads from the latter and diverges from the bit axis to open through the end of the body remote from the stem adjacent and forwardly in the direction of bit rotation from each of said arms, a concentric counterbore at the dis- 8 charge end of each said passage permanently seats a tungsten-carbide nozzle in end-flush relation with the adjacent body end, and a throat through each said nozzle converges on an elliptical curve from registration at its inner end with the associated passage to an outlet at its outer end having a diameter less than that of the passage.

References Cited in the file of this patent UNITED STATES PATENTS 2,022,734 Pearce Dec. 3, 1935 2,408,892 Stokes Oct. 8, 1946 2,507,221 Phipps May 9, 1950 2,648,525 Phipps Aug. 11, 1953 FOREIGN PATENTS 684,988 Great Britain Dec. 31, 1952 vides the free end of the associated arm 13 and opens through a portion of the leading face plane 14 thereof to define spaced fingers 13 thereon, in each of which fingers is slot-seated and permanently secured a tungstencarbide wafer 16' edge-fiush with its finger and in end projection as a chisel edge therebeyond exactly as set forth with respect to the wafers 16. The notches 24 may be disposed to divide the arms thereby interrupted into fingers of equal, or unequal, widths, as may be desired, and the notches in the separate arms of a given bit may be arranged to track for the development of an annular rib at the foot of a bore as the bit is rotated, as shown, or they may be located at different distances from the bit center in any desired staggered relationship, as may be deemed expedient for particular purposes.

When rotated with and as the penertating end of a drill line or string under pressure deriving from the weight of the tool assembly, the chisel edges of the wafers 16 and 16' plow out an annular channel about a central stub core accommodated and developed in the space between inner margins of the arms 13, which core steadies and guides the bit to keep the bore straight as it is deepened. The tungsten-carbide wafer 18 slot-seated in the boss 17 diametrically of the bit and in spaced relation with the adjacent edges of the arms 13 operates in engagement with the exposed end of the stub core to crush and disintegrate the latter as the bit descends, while the streams of coolant ejected at high velocity from the nozzles 22 soften and loosen the floor of the annular channel immediately in advance of the moving chisel edges and flush the cuttings away from the area being worked. The modification including the notches 24 functions as above set forth with the added advantage that a given bore area may be worked with a reduction in the chisel edge exposure for more rapid penetration in proportion to power input, the ribs and ridges left by the notches readily breaking up as the bit advances.

The permanent slot-seating of the tungsten-carbide inserts accomplished as shown and described protects the inserts against fracture and dislodgement and conditions the bit for continuous use until the wafers 16, or 16, are actually worn away. Whatever direction the bit is turned, the inserts 16, 16, 18, 19 and 22 are braced and protected by the metal of the bit elements wherein they are seated and are never subjected to forces tending to unseat them. As the bit is operated, the ends of the wafers 16 and 16' and the exposed surfaces of the inserts 19 efifectively resist abrasions imposed by the bore walls and thus maintain the bit size and consequent bore gauge; the softer metal of the bit arms and block being hence protected from excessive wear. The cutting edges of the wafers 16, 16 and 18 wear but slowly and the softer metal wherein they are seated correspondingly erodes to maintain the cutting edge exposure shown and described until the slot-seated inserts have been fully worn away, thus eliminating occasion for frequent removal of the bit from the bore and contributing an exceptionally long useful bit life. Despite the enhanced velocity of coolant discharge generated by the nozzles 22, the tungsten-carbide from which said nozzles are formed deforms but little during the working life of the bit and preserves the desired direction and effective velocity of the jet streams developed therethrough.

Since changes, variations, and modifications in the form, construction, and arrangement of the elements shown and described may be had without departing from the spirit of my invention, I wish to be understood as being limited solely by the scope of the appended claims, rather than by any details of the illustrative showing and foregoing description.

I claim as my invention:

1. A rotary drill bit comprising a body formed with a hollow, externally-threaded, attaching stem outstanding integrally and axially from one end thereof, integral arms outstanding radially and oppositely from said body and extending longitudinally of and beyond the body away from said stem, the outer margins of said arms determining maximum bit diameter in spaced parallelism with the body and stem axis and being transversely arcuate concentrically of the body and the inner margins of the arms paralleling the body and stem axis in a uniform spacing radially therefrom, tungsten-carbide blocks permanently slot-seated in and extending entirely across the free ends of said arms with their edges radial of the bit in a common plane perpendicular to the body and stem axis and exposed axially of the bit in a direction away from said stem, chisel edges on the exposed corners of said blocks leading in the direction of bit rotation, a cuneal boss fixedly projecting from said body between the inner margins of said arms with its apex diametric of the body and perpendicular to the diameter common to said blocks, a tungsten-carbide block permanently slotseated entirely along and to constitute the apex of said boss in edge exposure axially of the bit toward and inwardly of the bit from the plane of rotation common to the axially-exposed edges of said first blocks, and means for circulating coolant through said body.

2. The organization according to claim 1, wherein the chisel edge corners of the blocks slot-seated in the arms align diametrically of the bit.

3. The organization according to claim 1, wherein the blocks at the free ends or" the arms are mounted in filling relation within slots intersecting said free ends and opening through the tip and the inner and outer side margins of the associated arm in a considerable depth axially of the bit, the side wall of each such slot leading in the direction of bit rotation is radial of the bit, whereby to align the chisel edge corners of the blocks diametrically of the bit, and the ends of said blocks intersecting the inner and outer margins of the associated arm lie in and conform with the marginal surfaces thereby interrupted.

4. The organization according to claim 1, wherein the blocks at the free ends of the arms are mounted in filling relation within slots intersecting said free ends and opening through the tip and the inner and outer side margins of the associated arm in a considerable depth axially of the bit, the edge of each said block exposed radially of the bit inclines from its chisel edge corner into smooth mergence with the rounded end of that part of the associated arm trailing said block in the direction of bit rotation, the part of each arm leading in the direction of bit rotation is formed with a plane face parallel to and offset from a plane diametrically of the bit through the block chisel edge corners, which plane face at one side angularly adjoins the adjacent end of the body and at an opposite side overlies the associated slot-seated block, and the end of that part of each arm leading in the direction of bit rotation is beveled between the block and the adjacent side of said plane face to expose an area of the block contiguous to the block chisel edge corner as a narrow fillet radially of the bit and facing in the direction of bit rotation.

5. The organization according to claim 1, wherein the tungsten-carbide block carried by the cuneal boss is mounted in filling relation within a slot intersecting the boss and opening through the apex and opposite ends thereof in a considerable depth axially of the bit, ends of said block conform to the end faces of the boss thereby interrupted, and corners of the exposed edge of said block are constituted as chisel edges along the portions thereof leading in the direction of bit rotation;

6. The organization according to claim 1, wherein the stem hollow terminates in a domed chamber within the body, and the means for circulating coolant through the body comprises a passage small in relation to the chamber leading from the latter and diverging from the bit axis to open through the end of the body remote from the stem adjacent and forwardly in the direction of bit rotation from each of said arms.

7. The organization according to claim 1, wherein the 

